Lecture 9 Notes

Lecture 9 Alpine-himalayan orogeny: the building of the next supercontinent (Pangea II) Obduction: the process whereby we collide continents together. Theres no subduction (destroying crust) involved so theres not volcanoes, but theres lots of earthquakes. Most of the continents originated as small crustal pieces about the size of a province in Canada then the obducted together into larger masses. Relationship between tectonics and climate: tectonic processes can change climate on much larger time scales. The geology of Canada would be much different if it wasnt for the major orogenic belt, its formation changed global climates and led to the cooling over the climate. It was climate changes in east Africa which promoted human development, and allowed humans to leave Africa, this climate change was caused by alpine Himalayan orogeny. History doesnt repeat itself but it often rhymes: earths history is a succession of super continents. We are just about in the maximum extent of that process, the atlantic ocean will start to close, the pacific is already closing. Slide 4: Plate map red arrows show which direction the plates are moving in and the length shows the velocity. Parts of the pacific plate are moving quite fast headed right for Japan. Everything is headed towards south east Asia. Slide 5: Figure 2.29 in text book: it does into obduction and shows cross sections. Before india collided with asia there was an ocean the Himalayas were created from this obduction. Earthquake in Burma was the result of India being driven north. Its pushing into the Asian continent and spreading it as well, so youll see the little ladders, this is where the spreading is going on, there is also rift basins. The most important thing to get out of this diagram is that the effects of India being driven up are felt over a very large area; we can see that Afghanistan and Pakistan as well as southeast Asia are escaping. Slide 6: the collision started about 24 million years ago, this diagram shows a timeline, we can see the other Asian crust trying to escape, there is a subduction zone down by Indonesia. The mediteranian is a remnant of the ocean that lay between Africa and Europe, near India the ocean is completely gone, the Mediterranean is still there but it will be gone once Africa continues to collide with Europe, resulting mountain range is the SwissFrenchAustrian alps. Slide 7: the most common type of rock will be high grade metamorphic rocks, gneiss, high temperature. If you drive up north in Ontario you will see the roots of an old www.notesolution.com